From 8f89642fa10bb6ec02feaa8e3d1d62df671d0207 Mon Sep 17 00:00:00 2001 From: Andrzej Hajda Date: Mon, 21 Sep 2015 15:33:49 +0200 Subject: [PATCH] isdn: hisax: fix frame calculation Difference of unsigned values is also unsigned so it does not make sense to check its sign. The problem has been detected using proposed semantic patch scripts/coccinelle/tests/unsigned_lesser_than_zero.cocci [1]. [1]: http://permalink.gmane.org/gmane.linux.kernel/2038576 Signed-off-by: Andrzej Hajda Signed-off-by: David S. Miller --- drivers/isdn/hisax/hfc4s8s_l1.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/drivers/isdn/hisax/hfc4s8s_l1.c b/drivers/isdn/hisax/hfc4s8s_l1.c index 0e5d673871c0..9600cd771f1a 100644 --- a/drivers/isdn/hisax/hfc4s8s_l1.c +++ b/drivers/isdn/hisax/hfc4s8s_l1.c @@ -646,14 +646,14 @@ rx_d_frame(struct hfc4s8s_l1 *l1p, int ech) f1 = Read_hfc8_stable(l1p->hw, A_F1); f2 = Read_hfc8(l1p->hw, A_F2); - df = f1 - f2; - if ((f1 - f2) < 0) - df = f1 - f2 + MAX_F_CNT + 1; + if (f1 < f2) + df = MAX_F_CNT + 1 + f1 - f2; + else + df = f1 - f2; - if (!df) { + if (!df) return; /* no complete frame in fifo */ - } z1 = Read_hfc16_stable(l1p->hw, A_Z1); z2 = Read_hfc16(l1p->hw, A_Z2);